1. Field of the Invention
The present invention relates to a liquid silicone rubber coating agent composition that yields a cured product with excellent properties of adhesion to fiber, rubber strength, and blocking resistance and the like, as well as an air bag with a rubber coating layer comprising a cured product of such a composition.
2. Description of the Prior Art
Conventionally, silicone rubber-coated fabrics that have been produced with the aim of forming a rubber coating on the surface of fibers have retained the characteristic stickiness of silicone rubber, meaning the ease of operations such as cutting and stitching performed following coating has been very poor. In order to overcome these problems, a powder such as talc with superior properties of adhesion and slipperiness is typically dusted over the rubber surface. However, this method is not only costly, but the resulting powder dust can have a deleterious impact on human health. Furthermore, because the powder is simply adhered to the surface of the rubber-coated fabric, the powder is readily removed, meaning it is unable to provide a stable effect.
In order to overcome these problems, the compositions described below have been proposed. For example, a coating composition for a rubber-coated fabric prepared by adding a powder of an inorganic compound or organic compound with an average particle diameter of 0.5 to 20 μm selected from the group consisting of aluminum hydroxide, mica, dimethylsilsesquioxane, carbon, polyamide, and polyfluoroethylene to a rubber coating composition (patent reference 1); a coating composition for a low-tackiness rubber-coated fabric prepared by adding a drying oil compound selected from the group consisting of natural drying oils, modified natural drying oils, liquid diene compounds, and unsaturated fatty acid esters to a rubber coating composition (patent reference 2); a coating composition for a rubber-coated fabric with minimal tackiness of the surface of the rubber coating film, prepared by adding a hollow powder such as an aluminosilicate hollow powder, glass balloons, silica balloons, shirasu balloons, carbon balloons, alumina balloons, plastic balloons or a silicone resin hollow powder, or an alumina powder, glass powder or plastic powder, with an average particle size within a range from 10 to 300 μm, to a rubber coating composition (patent reference 3); and a coating composition for a rubber-coated fabric with reduced tackiness, prepared by adding a wet silica with an average BET specific surface area within a range from 150 to 250 m2/g and an average particle size of no more than 20 μm to a rubber coating composition (patent reference 4) have been proposed.
However, although all of these compositions provide improved workability properties following curing, the cured products are not able to provide satisfactory blocking resistance, while still retaining favorable levels of properties such as adhesion to fibers and rubber strength.
[Patent Reference 1] EP 0 712 956 A1
[Patent Reference 2] EP 1 013 817 A2
[Patent Reference 3] U.S. Pat. No. 6,420,037
[Patent Reference 4] U.S. Pat. No. 6,387,520